ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 609 



distinguishes three main types of bone structure — the lamellar, laminar, 

 and Haversian system types, which may occur pure or mixed. The 

 frog shows only lamellae ; the reptile shows laminae, formed by the 

 grouping and separating of the lamella by canals ; the highest grade — 

 the Haversian system — appears in outline in reptiles, but in its com- 

 plete form in birds and mammals. Many birds and mammals have 

 femurs predominatingly lamellar or predominatingly laminar, or mixed 

 lamellar and laminar. Many mammals show a complete mixed type, 

 lamellar, laminar, and Haversian. The author thinks that the structure 

 in any type is partly specific and partly due to the functional require- 

 ments of the bone. 



Red Blood Corpuscles of Mammals.* — E. Eetterer and Aug. 

 Lelievre find that the young stages are spherical or hemispherical, but 

 are deformed with extreme readiness. In the circulating blood the 

 corpuscles lose their spherical and hemispherical shapes, and become 

 bell-like or lens-like. The spherical and hemispherical stages may be 

 compared to the moon in its first quarter on a clear night ; the 

 haemoglobin-containing portion is like the luminous crescent, but there 

 is another portion without haemoglobin occupying the concavity of the 

 crescent. What happens is that the portion without haemoglobin is 

 lost as the corpuscles become older. 



Epithelial Cells of Mammalian Kidney .f — K. W. Zimmermann 

 describes the different kinds of elements — those at the beginning of the 

 " main portion " of the tubuli, with well-developed lateral ridges which 

 fit into indentations of adjacent cells ; those in the pars radiata, which 

 resemble truncated pyramids and have smooth sides ; the branched flat 

 cells of the isthmus ; and so on. 



Tendons of Wing and Leg in Bats, j — E. Retterer and Aug. 

 Lelievre have previously shown that in the muscles of the hind legs of 

 bats the framework of the muscle-fibre is much more developed than 

 the contractile myosarc, while in the muscles of the wings the myosarc 

 is abundant and remains fluid. 



They have gone on to study the differences in the tendons, using 

 embryos and adults of Vesperugo pipistrellus and Miniopteris schreibersii. 

 In the flexor muscles and tendons of the hind limbs there is no hint of 

 reduction — they are in fact better developed than in the wing ; this 

 shows that the winter-suspension implies energetic muscular contraction. 

 The tendons of the toes and of the thumb, and their fibrous sheaths, 

 are hypertrophied, and are transformed, partially at least, into vesiculo- 

 fibrous tissue. The tendons of the flexors of the wing are, as usual, 

 fibrous cords. 



Cytoplasm, Chondriosomes, and Chromidia.§ — Julius Schaxel 

 has studied in young ova of various Echinoderms the structure of the 

 cytoplasm, which appears so different with different modes of treatment. 



* C.H. Soc. Biol., lxxi. (1911) pp. 150-3. 



t Arch. Mikr. Anat., lxxviii. (l'Jll) Festschrift Waldeyer, pp. 199-231 (3 pis. 

 aud 1 fig.). J C.R. Soc. Biol., lxxi. (1911) pp. 67-70. 



§ Anat. Anzeig., xxxix. (1911) pp. 337-53 (1G figs.). 



